The present invention relates generally to the field of load producing springs for disk drive heads. More specifically, the invention relates to an improved spring design for providing a consistent load.
As is known in a disk drive, a magnetic head for reading and writing information on the disk is typically mounted on one end of a load beam spring. The other end of the load beam spring is attached to an actuator arm that positions the spring and head over a selected track on the disk.
A conventional load beam spring comprises a thin, usually triangular shaped metal piece having a spring area and a stiffened area. The stiffened area includes formed ribs or flanges along the perimeter and is intended to provide length without flexibility or compliance. Such springs are intended to provide a consistent load as well as low stiffness, so that any misalignment does not cause a significant change in the load.
The spring rate of such load beam springs is typically measured as a load change due to a vertical deflection at the read/write head and is commonly 60-100 grams per inch. Thus, disk drive assembly tolerances that cause misalignment result in load changes which cause the spacing of the read/write head to change with respect to the disk. If the read/write head moves too close to the disk, damage could result to either the head or the disk, and if the read/write head moves away from the disk, information may not pass between the head and disk. Lowering the load beam spring rate is therefore critical.
Common methods for reducing load beam spring rates are to use thinner metal. Additionally, it is known to cut a square hole from the center of the spring area. However, these methods for reducing the spring rate also lower the load beam spring natural frequencies of vibration which will cause read/write head positioning instabilities. Such positioning errors will restrict the information flow between the head and the disk.
The previously mentioned methods for reducing the spring rate may also have a detrimental effect on the stability of the spring. Both reducing the spring thickness and taking metal away from the center of the spring reduce the cross-section in a manner that increases the stress in the load beam spring. Therefore, during handling and loading/unloading procedures, the load beam spring may be damaged, resulting in a load change on the read/write head. The load change on the read/write head will cause the head to damage the disk or move away from the disk, causing information transfer problems.
As read/write heads and disks continue to decrease in size, head to disk spacing becomes even more critical. At the same time, positioning requirements continue to demand higher load beam spring natural frequencies. Therefore, there is a need for an improved load beam spring area that minimizes spring rate, increases load beam natural frequencies, and minimizes the stress in the load beam spring.